Wireless telegraphy.



Nu. 706.735. Patented Aug. l2, I902.

I B1 A. FESSENDEN.

WIRELESS TELEGRAPHY.

(Application filed Dec. 1H5,v 1899.)

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Patented Aug; I2, I902.

B. A. FESSENDEN. WIRELESS TELEGRAPHY.

(Application Med Dec. 15, 1899.)

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(No Model.)

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No. 706,735. Patented Aug. l2. i902.

nfA. FESSENDEN.

WIRELESS TELEGRAPHY.

(Application filed Dec. 15, 1899.)

(No Model.) 3 Sheets-Shaat 3.

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UNITED STATES,"

PATENT OFFICE.

REGINALD A. FESSENDEN, OF ALLEGHENY, PENNSYLVANIA.

WIRELESS TELEG RAPHY.

$PECIFIGATION forming part of Letters Patent No. 706,735, dated August12, 1902. Application filed December 15,1899. Serial No. 740,429. (Nomodel.)

To aZZ 1072 0112, it may concern:

Be it known that I, REGINALD A. FESSEN- DEN, a citizen of the UnitedStates, residing at Allegheny, in the county of Allegheny and State ofPennsylvania, have invented or discovered certain new and usefulImprovements in Wireless Telegraphy, of which improvements the followingis a specification.

The invention described herein relates to certain improvements in theelectrical transmission of signals from one station to another withoutthe use of cond uctors connecting such stations.

In the methods heretofore employed the electromagnetic Waves generatedat the receiving-station produce voltages in the receiving circuit.These voltages passing through a suitable material normallynonconductive render the same conductive, and thereby permit the passageof a current through a circuit in which said material, usually termed acoherer, is included. After the cessation of the voltages produced byeach series of electromagnetic waves generated at the sending-stationthe coherer must be operated on in some Way to restore it to normal ornon-conductive condition.

The object of the present invention is to provide for the generation bycurrents produced by electromagnetic waves of currents in a secondelement or circuit and by the reaction of the current in this secondelement or circuit on the field formed or produced by the currents inthe receiving-Wire to produce motion which is directly or indirectlyobserv able.

In. general terms the invention consists in the generation byelectromagnetic waves of a current directly or indirectly in coils atthe receiving-station, the current in said coils inducing a current inanother element or circuit which is arranged in such relation to thecoils that the current induced therein reacts with the field produced bythe coils, thereby producing motion.

The invention is hereinafter more fully described and claimed.

In the accompanying drawings, forming a part of this specification,Figure 1 is a diagrammatic view showing the arrangements employed at thesending and receiving s1ations. Figs. 2 and 3 are diagrammatic viewsillustrating modifications of the receiving apparatu s. Fig. 4 is a sideelevation of the apparatus shown in Fig. 3, and Fig. 5 is afurthermodiiication of the receiving apparatus.

The apparatus employed at the sending station may be similar to that nowin use for the generation of electromagnetic waves and consists of aninduction-coil 1, having its primary coil in circuit with a generator 2,saidcircuit having a make-and-break mechanism 3 included therein. One ofthe discharging knobs or terminals 4 is connected with the verticalsending-conductor 5, While the other knob or terminal is grounded. I

have found that by placing a capacity form ed by a body 5 of conductingmaterial having a comparatively large radiating-surface the Wavesgeneratedat the sending-station have a very much higher energy, therebycorrespondingly increasing the effect or energy of the current producedin the receiving-conductor.

The terms sending-conductor and receiving-conductor are employed hereinas indicatingallofthecircuitsatthe sendingand receiving stations fromtop to ground, if grounded, or if not grounded from one extreme end tothe other extreme end, including all apparatus in series with thecircuits, While the term radiating portion indicates all of thesending-conductor from top or extreme end of same to point of junctionwith the apparatus for effecting the oscillatory charging anddischarging thereof, such as sparking terminals,transformer-coils,armature windings, &c. By the term electromagneticwaves as used herein is meant Waves of a wave length long in comparisonwith the Wave length of what are commonly called heat-waves or radiantheat. Bygroundedconductoris meant a conductor grounded either directlythrough a capacity, an inductance, or a resistance, so that the currentsin the conductor flow from the conductor to ground, andvice versa, whenelectromagnetic Waves are being generated. The terms tuned and resonantare used herein as one including the other. By the term current-operated Waveresponsive device as used herein and by me generally ismeant wave-responsive devices having their contacts good contacts andoperated by currents produced by electromag- .preferably formed by asilver ring.

netic waves. They are hence to be distinguished from wave-responsivedevices depending for operation upon varying contact resistance.

At the receiving-station the receiving-conductor is formed by a wire orwires 0, projecting up vertically or at an inclination to a suitableheight, which are also grounded. A coil or coils 7 are arranged in thecircuit of the receiving-conductor 6, and an element or coil of wire 8,forming a closed circuit, is support- -ed with a freedom of movement insuch relation to the coil or coils 7 that the current produced by theelectromagnetic waves will induce a current in the element 8. Theelement 8 is supported, preferably, in such manner that a plane at rightangles to its axis will form an angle of approximately forty-fivedegrees, (45,) with a plane at right angles to the axis of the coils 7,so that the reaction of the current induced in said element with thefield produced by the coils 7 will cause the element 8 to move withreference to the coils 7. This motion of the element maybe observable bymeans of a mirror9, attached thereto, reflecting a beam of light on ascale, or said element may form a part of the circuit of arecordingsiphon, &c.

As shown in Fig. 2, the coils 7 may be connected to the secondary coil11 of a transformer whose'primary coil 12 is connected in series withthe receiving-wire.

A desirable means for transforming the electromagnetic waves intorecordable motion is shown in Figs. 3 and 4. The element 8 is balancedon supporting-rods or knife-edges 13, one of which is formed of a goodelectrical conductor, as silver, the .element 8 being A carbon block 14is so arranged that a portion of the ring between the supporting-rodswill normally rest lightly thereon. This microphonic contact, theconducting pivotal support, and the portion of the ring between themform parts of an electric circuit, which also includes a generator 15and a recording instrument 16 as a telegraphic sounder or the receiverof a telephone. When a current is generated, as above described, in thecoil 7, the element or ring 8 will be caused to press on the carbonblock, thereby increasing its conductivity. lVhen using atelephone-receiver as a recording instrument, the generator15 ispreferably of a character capable of producing an alternating current,as such current causes a constant vibration of the diaphragm, thevibrations increasing in intensity with an increased flow of current inthe circuit. This increase in intensity of action with increased flow ofcurrent is characteristic of this form of receiver and also of the formshown in Fig. 1. In this itis sharply difierentiated from such devicesas the coherer, which either give a strong indication or do not giveany. This characteristic is advantageous in that if the signal sentsay adot-be too weak to give an action of the full intensity it may stillinmost cases be read and -not missed entirely, which is of value insending code-messages.

In the construction shown in Fig. 5 the circuit of the generator isdivided, one branch includinga coil 16 and connected to a microphoniccontact 14*, while the other branch of the circuit includes areversely-wound coil 16 and is connected to a microphonic contact 14These contacts are arranged on opposite sides of the ring 8 and are soadjusted that the ring will ,normally rest equal on both blocks, so thatan equal current will flow through both of the coils 16 16 therebymaintaining a magnetic bar 17, suspended between the coils inequilibrium with relation to the coils. Adjustable resistances may beplaced in the circuits of the coils, thereby avoiding the necessity ofdelicate adjustments of the carbon blocks. When the coils and the ringor element 8 are energized, the pressure of the latter on one contact isincreased and that on the other decreased, thereby correspondinglychanging the resistances in the two branches. The increased flow ofcurrent through one coil and decreased flow through the other coil, dueto the change in resistances, will produce a greater movement of themagnetic bar 17 than if only a single coil were used. The movement ofthe bar 17 can be rendered observable in many ways known in theelectric-signaling art-as, for example, by securing a mirror thereon.

As shown in Fig. 1, a condenser 19 may be connected in shunt with thefield coil or coils 7 for the purposeofpbtaining as largeacurrent aspossible in the field-coil 7, as this increase in current will give agreater torque to the ring 8. When no condenser is employed, this largecurrent must flow in the vertical wire, and there would be great loss ofenergy on account of the resistance of wire 6, and, further,without thecondenser alarge amount of energy will be required to give the staticalcharge to the receiving-conductor. Hence on account of the small energyfurnished by the wave a large current cannot be obtained in field coilor coils 7 without the condenser. By employing a condenser of the propersize current in wire 6 may be made to have a value equal to thedilference between the current in thefield coil or coils and the currentin the condenser. Either of these currents may therefore be large andeither or both may be used to produce motion, while the current in wire6 may be kept so small that there is practically no loss of energy onaccount of its resistance or of the statical charging of the receiver,and all the energy may be used in producing motion. Without thecondenser the current in the field coil or coils 7will be practically aquarter-phase behind the voltage on account of the self-inductive lag-inthe fieldcoil. If the condenser. were substituted for the field-coil,there would be a current in it nearly a quarter-phase in advance of thevoltage due to the capacity lead. When both the field-coil and thecondenser are introduced one in shunt with the other, there will be acurrent in the field coil or coils lagging ninety degrees (90) and inthe condenser a current leading ninety degrees, (90.) The sum of twocurrents one hundred and eighty degrees apart in phase is equal to thedifference between their values. Hence if there is a current in thefield coil or coils of one ampere and in the condenser a current ofnine-tenths of an ampere the current in the receivingwire 6 will beone-tenth of an'ampere.

By the employment of a condenser in shunt with the coil or coils 7 thecurrent in the receiving-wire is reduced without reducing the current inthe coil or coils 7, so that the resistance drop, which is at timessufficiently great to afiect the operation of the system, is

' eliminated or so reduced as not to have any material efiect.

It is preferred to place a shunt-circuit containing a condenser acrossthe terminals of the induction-coil at the sending-station for thepurpose of maintaining sustained radiation. This shunt-circuit must betuned to the receiving-conductor; otherwise the oscillations produced byit will have no action upon the wave-responsive device at thereceiving-station. This shunt-circuit by virtue of its capacity storesup an additional amount of energy, and when a spark passes across thegap, since the sending-conductor can radiate energy at a given rate, itmust continue to radiate for a longer time in order to dissipate thisadditional stored-up energy.

I am aware that apparatus consisting of a fixed primary and a movablesecondary circuit has been used for detecting oscillatory currents. Thisapparatus was a modified form of an earlier alternating voltmeter, asilver disk or thick-rimmed annulus being substituted for the Wire coilused in the voltmeter and delicately suspended so as to have a longperiod of swing. This apparatus was used not for the purpose ofdetecting electromagnetic waves emitted and received by unclosedcircuits, but for detecting the magnetic inductive efiects which oneclosed circuit (having rapidly-oscillating currents produced in it by atransformer, Hertz oscillator, or other suitable means) produced onanother closed circuit. The effects to be obtained by such an apparatuswere therefore different in kind from those sought in wirelesstelegraphy and the method of producing them were different from thatdescribed herein. This Northrup apparatus was used todetect magneticinductioneffects to a distance of approximatelyone hundred yards.Although distances somewhat longer could doubtless have been attainedwith such apparatus, the method employed by Northrup is not availablefor commercial Wireless signaling, as magnetic induction effects falloff as the cube of the distance, and approximately ten thousandsofmillions times the energy would be i wireless telegraphy, as themovable member consists of a disk or thick-rimmed annulus, whereas themovable member of the receiving mechanism for wireless telegraphy shouldbe a ring formed of thin wire (indicated at 8 in the drawings) having aratio of internal and external diameters equal or approximately equal tounity. If a disk or thickrimmed annulus should be used as the movablemember of the receiving mechanism for wireless telegraphy, theefficiency of such mechanism would be so greatly reduced as to render itinoperative, for the reason that the currents induced in the disk orthick-rimmed annulus tend to get as near as possible to the center ofsuch parts, and thereby weaken the reactive effect between the fixed andmovable parts and to exert small torque, and, further, as the disk andthick-rimmed annulus have low self-induction the currents induced inthem tendto get out of phase with the currents in the fixed coil orcoils, and

hence the torque is weakened. Moreover,

the period of oscillation of a disk or thickrimmed annulus for a givenrestoring force is so long that extremely-powerful restoring forces mustbe used to enable a mechanism having such a movable member to recordsignals at commercially-practical speeds, and since the force varies asthe square of the speed deflecting forces many thousands of timesgreater must be employed than is required in the receiving mechanismdescribed herein. In other words, the thin light ring 8 will work withbut a fraction of the energy required to operate a disk or thick-rimmedannulus. By the employment of a thin ring of good conducting materialand a fixed coil of few turns, as shown in the drawings, the electricalforces between fixed and movable members of the receiving mechanism arerendered more efficient, and hence the force necessary forcommercially-practical signaling is greatly lessened.

The inapplicability ofthe Northrup apparatus is further shown by thefact that the coils of the fixed member of his apparatus consist of alarge number of turns of wire, so that the resistance in such coils ishigh, whereas a commercially-practicable instru ment for wirelesstelegraphy should have its fixed coil or coils formed by a few turns ofwire, and consequently of low resistance. By the employment in thereceiving instrument of a fixed coil or coils of few turns and a movablemember formed by a thin light ring of highly-conducting wire highresonance effects combined with a rapid natural period of the movingpart and a maximum efficiency are attained and the advantageous use oftransformers, as in Fig. 2, is rendered possible.

It is characteristic of the method shown that the. receiving mechanismsare actuated by currents produced by electromagnetic waves and not byvoltages, as in the case of the coherer. Hence when the receivingmechanisms described herein are used in connection with a secondarycircuit said circuit is controlled by the currents generated byelectromagnetic waves and not by voltages. It is also characteristicthat when a secondary circuit is used in connection with the type ofwave-responsive device shown in Figs. 3, 4, and a portion of thesecondary circuit is traversed and controlled by currents produced byelectromagnetic waves. It is further characteristic of my improvedsystem that the indications produced by the receiving mechanism hereindescribed are dependent upon the total amount of energy emitted to formthe signal and are not, as in the case of the coherer, dependent uponthe maximum of the voltage.

I claim herein as my invention 1. As an improvement in the art oftransmittingsignalselectricallyby electromagnetic waves the methodherein described, which consists in the generation of electromagneticwaves at one station and transforming the energy of the currentsgenerated by such waves at the receiving-station into the energy ofmotion, that is without the necessary interposition of a secondary orauxiliary generator for the production of such motion, substantially asset forth.

2. As an improvement in the art of transmitting signals between stationsby electromagnetic waves, the method herein described which consists incausing the radiation of electromagnetic waves from a groundedconductor, generating voltages by such waves in a conductor at thereceiving-station and transforming the energy of each of said voltagesinto the energy of motion, substantially as set forth.

3. As an improvement in the art of transmitting signals electricallybetween stations by electromagnetic waves, the method herein describedwhich consists in producing an electromagnetic field'in a receivingmechanism consisting of relatively fixed and movable members arranged inoperative relation to each other by the generation of electromagneticwaves at the sending-station, thereby causing a movement of one of theparts of the receiving mechanism, substantially as set forth.

4. As an improvement in the art of transmitting signals electricallybetween stations by electromagnetic waves, the method herein describedwhich consists in the generation of a current or currents in a portionof a receiving mechanism consisting of relatively fixed and movablemembers by the generation of electromagnetic waves at thesending-station and then producing a current or currents in the otherportion of the receiving mechanism by the current or currents generatedby the.

electromagnetic Waves, whereby one part of the receiving mechanism iscaused to move relative to the other part,substantially as set forth. 7

5. As an improvement in the art of transmitting electrical energy byelectromagnetic waves the method herein described, which consists inmaintaining a secondary circuit in an energized condition andcontrolling the energy of said circuit by current efiects produced byelectromagnetic waves flowing through a currentoperated wave responsivedevice forming a portion of the secondary circuit.

6. As an improvement in the art of transmitting electrical energy byelectromagnetic waves the method herein described, which consists inprolonging the oscillations of an energy-radiating conductor by energyfrom a source external to the radiating-conductor and tuned to theperiod of the radiating-condoctor, substantially as set forth.

7. As an improvement in the art of transmitting electrical energy byelectromagnetic waves the method herein described, which consists in thegeneration of electromagnetic waves at one station and transforming theenergy of the currents generated by such waves at the receiving-stationinto the energy of motion, varying the motion thus produced by varyingthe amount of energy delivered at the receiving-station without thenecessary interposition of a secondary or auxiliary generator for thepurpose of such motion, substantially as set forth.

8. As an improvement in the art ot'signaling by electromagnetic wavesthe method herein described, which consists in generatingelectromagnetic waves in a grounded conductor at the sending-station,receiving such waves at the receiving-station and transforming theenergy of electromagnetic waves so received into the energy of motion bymeans of a receiving instrument having a low resistance, substantiallyas set forth.

9. As an improvement in the art of transmitting electrical energy, themethod herein described, which consists in varying the conductivity of asecondary circuit at the receiving-station by motion produced bycurrents generated by electromagnetic waves, substantially as set forth.

10. As an improvementin the art of transmitting electrical energy, themethod herein described, which consists in the generation ofelectromagnetic waves at one station, transforming the energy of thecurrents generated waves into the energy of motion, varying the currentsin two ormore local or secondary circuits by such energy of motion,transforming i 1 Q the energy of the varied currents into the en- 1REGINALD FLSSENDEN' ergy of motion and causing the energies of motion soproduced to operate in the same direction, substantially asset forth.

In testimony whereof I have hereunto set my hand Witnesses:

DARWIN S. WOLCOTT, F. E. GAITHER.

